Method and apparatus for introducing reagents into liquid suspensions



Nov." 19, 1935. K, E, STUART 2,021,616

METHOD AND APPARATUS FOR INTRODUCING REAGENTS INTO LIQUID SUSPENSIONS INVENTOR.

3'Sheets -S heet 2 K. E. STUART [Filed Nov. 9, 1.934

Nov. 19, 1935.

METHOD AND APPARATUSfoil-INTRODUCING nmemuws INTO LIQUID susPENs1 oNs I N VEN TOR. /,MW

K. E. STUART Nov. 19, 1935.

METHOD AND APPARATUS FOR INTRODUCING REAGENTS INTO LIQUID SUSPENSIONS s Sheets- Sheet :5

Filed Nov. 9, 1954 I INVENTOR.

Patented Nov. 19, 1935 METHOD AND APPARATUS FOR INTRO- DUCING REAGENTS INTQ LIQUID SUS- PENSIONS Kenneth E. Stuart, Merion, Pa... assignor to Hooker Electrochemical Company, New York, N. Y.,' a corporation oi New York Application November 9, 1934, Serial No. 752,340

12 Claims.

My invention has for its object to secure more rapid diil'usion of the reagent and more particularly when it is gaseous, throughout the liquid oi the suspension and to provide simple apparatus for so doing.

One characteristic application of my invention is to the bleaching oi paper pulp, and more particularly to those processes which involves apreliminary chlorination for the purpose oi removing undesirable non-cellulosic constituents the bleaching of. which needlessly consumes bleaching agents, while at the same time exposing the cellulose to unnecessary degradation.

It is well known that when chlorine is injected into water it tends to hydrolyze, forming both hydrochloric and hypochlorous acid. The former is of no value in the process of bleaching paper pulp. The latter is a very active oxidizing or bleaching agent and to that extent is useful.

- Nevertheless, if allowed to do so, it attacks and weakens the fiber. It is therefore important to perform the bleaching operation quickly. The dark color of wood fiber is due principally to lignin and. other non-ceiluloslc constituents. It is these constituents that must be removed or bleached,

the cellulose itself being mostly white and requiring little or no bleaching. The bleaching operation can therefore be expedited by first removing most of the dark constituents. These constituents can be rendered more soluble and hence more v easily removable by chlorination. Therefore the first step in modern bleaching operations is a chlorination and this should be eifected as rapidly and thoroughly as possible. I

The hydrolysis of chlorine in water is not instantaneous and does not go on indefinitely. Only about one tenth of a per cent of hypochlorous acid can ordinarily be built up in a water solution. After that, the chlorine begins to go into solution. When the chlorine in solution has reached about one hall or one per cent, the chlorine ceases to go into solution, commences merely to bubble through the water. In order to contact chlorine rapidly with paper pulp it is therefore necessary to indect it more rapidly than it can hydrolyze orgo into solution, 1. e., it must be inpipe or porous diiluser, or to mix it with a stream of water in a water-operated'injector and introduce the stream of water and chlorine through a periorated pipe. In the latter case, between the injector and the perforated pipe there is a time interval during which hydrolysis is proceeding. Moreover, if the paper pulp is circulating the per- 5 fo'rated pipe itself projecting into the stream acts as an obstacle to flow and tends to cause irregular distribution of the chlorine throughout the mass of pulp.

My invention resides in the discovery that an injector may be submerged in the water suspension oi pulp in such a way that the stream of water and chlorine impinges directly upon the material to be chlorinated at the very mouth of the injector, thus eliminating the time interval 15 just referred to, during which hydrolysis is taking place. Moreover, it the pulp is circulating, as in the type of commercial apparatus known as a bellmer", the injector may be spread out into a fan and built intothe bottom oi the bellmer, so 20 that it will deliver the chlorine across the width of the bellmer while ofiering no resistance to flow. If desired, the thrust of the jet oi water and chicrine may be utilized to assist the flow by giving to the jet a. forward component.

My invention will be better understood by reference to the drawings, in which Fig. i is a plan view of a bellmer embodying two of my injectors.

Fig. 2 is an elevation of the same.

Fig. 3 is an enlarged plan view of my injector.

Fig. 4.- is a cross-section through my injector along the line H of Fig. 3, looking in the direction of the arrows, to a still more enlarged scale,

Fig. 5 is a greatly enlarged sectional view of the 35 water pipe of my injector, showing the form and construction of the orifices therein.

Referring to Fig. l:

I is the concrete wall of the bellmer and 2 the I engine which lifts the stream of water and pulp understood from Figs. 3 to 5. From these figures it will be seen that the. injector consists of a tubular casing 6 in which is co-axially aligned a pipe 'I which enters casing 8 through the stufilng box 8. Pipe I is closed at one end by plug 9.

'I'heother end of pipe I is connected through elbow III and pipe H to a source of water under pressure, (not shown) as a city water main. Between casing 6 and pipe 1 is an annular clearance l2, which is connected through pipe ll, elbow I4 and pipe IE to a source of chlorine under pressure, as a commercial chlorine shipping container (not shown). Along one side of easing 6 is formed a slot l6, which has a filleted approach and fiared exit, the whole constituting a venturi ll, of which the slot l6 constitutes the throat. Along one side of pipe 'I is a row of orifices l8, l8 directed into the throat of the venturi I1. The orifices l8 are preferably of the conical type in which the diameter diminishes in the direction of fiow. In this type'of orifice the molecules of water are crowded toward each other in passing through the restriction and rebound when beyond it, so as to follow paths diverging at approximately the angle of the cone which constitutes the orifice itself. This is illustratedby the dotted lines in Fig. 4. The molecules of water similarly diverge in every other plane passing through the axis of the cone. It is this which induces the zone of reduced pressure at the throat of the venturi; that is to say, the spreading apart of the molecules creates voids between them into which the gas contained in the annular clearance I2 fiows to satisfy the partial vacuum in these voids. In this way the stream of water is for all practical purposes atomized. The gas is likewise atomized and the molecules of gas are intimately diffused through the molecules of water, in accordance with the theory of injectors.

The orifices l8 are aligned with the throat l6 of venturi l1 and spaced apart at such a distance that their streams contact and blend into a continuous sheet of water at the throat of the venturi. Thus the jet takes the form of a sheet of water and chlorine which may be extended transversely of the stream of pulp so as to better distribute the chlorine to the pulp, as illustrated in Fig. 1. I

The entire injector assembly, comprising cas- -ing I, venturi l1 and pipe 1, etc., may be let into the concrete fioor of the bellmer and the venturi directed upwardly and forwardly with the mouth of the venturi flush with the floor of the bellmer, as illustrated in Fig. 4. With this construction theinjector offers no obstruction to flow of the pulp but, on the contrary, the thrust of the jet tends to assist the flow.

The casing 6, which is preferably integral with venturi l1, may be of chemical stoneware, which is entirely unaffected by wet chlorine. The pipe I, plug 9, elbows l0, l4 and pipes II, I! and 15 may be of hard rubber, pipes and fittings of this material in all standard sizes being now commercially available. The orifices ll are preferably formed in pipe I itself by drilling through both sides, reaming out one row of holes from the inside to give the conical shape and plugging the opposite row of holes, as illustrated in Figs. 4 and 5.

When the water and chlorine are shut off-from pipes, H and I5 respectively the water in the bellmer will back up into these pipes as high as the water level in the bellmer. These pipes should therefore be of hard rubber up to this level, beyond which point ordinary steel pipes may be used. The pulp in the bellmer will not back up into annular clearance I! as its consistency is such that it packs loosely into the venturi and bridges over the throat' 16. It cannot therefore enter clearance I! or orifices 18, to any considerable extent. Any loose individual fibers that the streams of water and chlorine are turned on.

My invention therefore provides a simple, din-Se ble and nearly trouble-proof apparatus that is at the same time more eflicient than any hereto- 5 fore known, in that the chlorine is better 'diflnsed throughout the mass of pulp with less time for hydrolysis and no obstruction to flow.

While I have illustrated my invention as applied to the chlorination of paper pulp in a bellmer, I 10 do not. wish to be limited thereto, as it is obviously suited. to other purposes, and in general-to any situation in which it is important to rapidlydifluse a reagent into a liquid suspension of finely divided solids. Neither do I wish to be limited to 15 the exact construction illustrated, as many modifications in design and materials of construction are obviously possible.

For example, the invention is not limited to the type of jet illustrated but, on the contrary, 20 any type of simple or multiple jet directed at any angle is within the scope of the invention, provided it is submerged in such a way that the stream of liquid and reagent is delivered directly against the material to be reacted upon, in con- 25 tradistinction to the prior practice of mixing the liquid with the reagent at a distance and conveyingit to the reaction zone, as through a pipe.

What I claim is:

1. An apparatus for introducing elemental 30 chlorine into a body of pulp'in a water suspension comprising in combination with an opentype container for said suspension an injector and connections for conveying water and chlorine under pressure thereto, said injector being :5 completely submerged beneath the surface of the suspension near the bottom of said container and adapted to. deliver its stream 0! water and chlorine directly against 'the suspension and means for circulating said suspension.

2. An apparatus for introducing elemental chlorine into a body of pulp in a water suspension comprising in combination with an opentype container for said suspension an injector terminating in a venturi and connections for 45 conveying water and chlorine under pressure thereto, said injector being completely submerged beneath the surface of the suspension near the bottom of said container and adapted to deliver its stream of water and chlorine against 50 the suspension at the mouth of the venturi and means for circulating said suspension.

3. An apparatus for introducing elemental chlorine into a water suspension of pulp flowing at relatively low velocity in a bellmer compris- 55 ing in combination with said bellmer and the pulp circulating means associated therewith an injector terminating in a venturi and connections for conveying water and chlorine under pressure thereto, said injector being set into the do bottom of the bellmer with the mouth of the venturi flush with the surface thereof.

4. An apparatus for introducing elemental chlorine into a water suspension of pulp flowing at relatively low velocity in a bellmer com- 55 prising in combination with said bellmer and the pulp circulating means associated therewith an injectorand connections for conveying water and chlorine under pressure thereto, said injector being submerged in the suspension near 10 the bottom thereof and delivering its stream of water and chlorine in a direction having a forward component with respect to the direction of flow.

5. An apparatus for introducing elemental 15 chlorine into a water suspension of pulp flowing at relatively low velocity in a belliner comprising a tubular casing extending transversely -oi! said flow and submerged at the bottom or said suspension, a pipe leading from a source of water under pressure and passing through a stufling box into said casing in co-axial alignment therewith, said pipe terminating within said casing in a closed end, a clearance of annular cross section between said pipe and easing, a connection to said clearance from a source of chlorine under pressure, a slot along one side of said casing and a row of orifices along one side of said pipe directed into said slot, said orifices being conical, with the' smaller end outward, whereby the stream from each orifice is caused to fly into rapidly divergent droplets, said orifices being so spaced that the streams therefrom contact each with the aujacent streams near the entrance to "said slot and form a continuous sheet of water substantially filling the cross section of the slot, said slot having the form of an elongated venturi adapted to cooperate with the jets to create a zone of reduced pressure at the entrance to the venturi, the whole constituting an eflicient mjector in which chlorine is atomized and diffused throughout the water of the jet and delivered by it directly against the pulp.

6. The method of reacting elemental chlorine with a body of pulp in a water suspension which comprises introducing the chlorine into an atomizing jet of water completely submerged beneath the surface of the suspension and impinging directly upon the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed state with a large body of pulp to produce chiefly a chlorinating eilect upon the pulp.

7. The method of reacting elemental chlorine with a body of pulp in a water suspension which comprises introducing the chlorine into an atomizing jet of water upwardly directed from the bottom of the suspension and impinging directly upon the suspension while circulating the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed condition with a large body of pulp to produce chiefly a chlorinating efiect upon the pulp.

8. The method of reacting elemental chlorine with a body of pulp in a water suspension flowing at relatively low velocity which comprises introclucing the chlorine into anatomizing jet of Water completely submerged beneath the surface of the suspension and impinging directly upon the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed condition with a large body of pulp to produce chiefly a chlorinating effect upon the pulp. 5

9. The method of reacting elemental chlorine with a body of pulp in a water suspension flowing at relatively low velocity in agravity stream which comprises introducing the chlorine into an atomizing jet of water completely submerged beneath the surface ofthe suspension and impinging directly upon the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed condition with a large body of pulp to produce chiefly a chlorinating effect uponthe pulp.

10. The method of reacting elemental chlorine with a body of pulp in a water suspension flowing at relatively low velocity in a gravity stream which comprises introducing the chlorine into an atomizing jet of water upwardly directed from the bottom of the suspension and impinging directly upon the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed condition with a large body of pulp to produce chieflly a chlorinating efiect upon the pulp.

11. The method of reacting elemental chlorine with a body of pulp in a water suspension flowing at relatively low velocity in a gravity stream which comprises introducing the chlorine into an atomizing jet of water upwardly directed from the bottom of the suspension and impinging directly upon the suspension and forwardly directed with respect to the flow of the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed condition with a large body of pulp to produce chiefly a chlorinating effect upon the pulp.

12. The method of reacting elemental chlorine with a body of pulp in a water suspension flowing at relatively low velocity in a gravity stream which comprises introducing the chlorine into a plurality of atomizing jets of water spaced transversely of said flow, upwardly directed from the bottom of said suspension and impinging directly upon the suspension, whereby the chlorine is quickly and intimately contacted in finely dispersed conditions with a large body of pulp to produce chiefly a chlorinating effect upon the pulp.

KENNETH E. STUART. 

